Antibacterial polyurethane insole material and preparation method thereof

Abstract

The invention relates to an antibacterial polyurethane insole material and a preparation method thereof. The problems that in the prior art, the antibacterial property of a polyurethane insole material is not lasting, and the mechanical property is reduced are mainly solved. According to the technical scheme, the novel antibacterial polyurethane insole material and the preparation method thereof are adopted, the novel antibacterial polyurethane insole material is composed of a component A and a component B according to the weight fraction ratio of 100: 68-82, the component A comprises 50-60 parts by weight of polyether polyol A1, polymer polyol A2, a catalyst, a chain extender, a cross-linking agent, water, a pore opening agent and a metal complex quaternary ammonium salt antibacterial agent, and the component B comprises 50-60 parts by weight of polyether polyol A1, a polymer polyol A2, a catalyst, a chain extender, a cross-linking agent, water, a pore opening agent and a metal complex quaternary ammonium salt antibacterial agent; and the component B is a prepolymer which is based on polyether polyol A1 and is terminated by polymethylene polyphenyl isocyanate and dimethyl diphenylmethane diisocyanate, so that the problem is well solved, and the polyurethane insole material can be applied to the polyurethane insole material industry.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane foam products, in particular to an antibacterial polyurethane insole material and a preparation method thereof. BACKGROUND

[0002] Polyurethane foam is widely used in insole production due to its light weight, good elasticity, excellent cushioning performance and other characteristics. However, traditional polyurethane foam insoles are prone to bacterial growth due to foot sweating during long-term use, resulting in odor and even foot diseases. The performance indicators of ordinary polyurethane insoles generally include: density of 150-250 kg / m 3 , Shore C hardness of 30-40, rebound rate generally less than 40%, tensile strength of about 400-500 kPa, elongation at break of 100-130%, and compression permanent set generally greater than 8%. These indicators show that ordinary insoles have obvious deficiencies in mechanical properties and durability, especially in terms of rebound and deformation resistance, which can easily cause problems such as collapse and deformation during use, affecting comfort and service life.

[0003] In the prior art, although attempts have been made to improve the antibacterial properties of polyurethane foam by adding antibacterial agents, there are often problems such as uneven dispersion of antibacterial agents, short antibacterial effect, or the addition of antibacterial agents affecting the foaming performance of the foam, resulting in increased density and decreased rebound.

[0004] Chinese patent CN109096464B discloses a breathable insole and a preparation method thereof, which is prepared by reaction of A and B components. Although it has certain breathability and mechanical properties, the specific data of rebound rate and compression permanent set are not disclosed in the scheme. The molecular weight of the polyether polyol used is relatively low (4500-7000), and the rebound rate is 35%-40% and the compression permanent set is >8% after testing. The mechanical comprehensive performance is still not ideal, and there is still room for improvement in terms of rebound and compression permanent set. Moreover, the problem of long-lasting antibacterial properties has not been systematically solved.

[0005] Chinese patent CN115678097A relates to a medical high-absorbency polyurethane foam dressing, which achieves antibacterial function by soaking the material in an antibacterial impregnating solution containing composite zinc oxide and other components after foaming. Although this method can impart certain antibacterial properties to the material, the antibacterial agent only exists through physical adsorption or surface bonding, and cannot form a chemical bond with the polyurethane molecular chain, resulting in the loss of antibacterial components during washing or use. After 20 washes, the antibacterial rate decreases to less than 60%, the antibacterial durability is poor, and it cannot meet the use requirements of insole products that need to be washed multiple times.

[0006] Therefore, it is of great significance to develop a preparation method of polyurethane foam shoe pad with low density, high resilience, low permanent deformation and persistent antibacterial property, and the antibacterial component is permanently combined by chemical bond, and the shoe pad is resistant to washing. SUMMARY

[0007] One of the technical problems solved by the present application is that the existing antibacterial polyurethane shoe pad material has the problems of non-persistent antibacterial property and decreased mechanical property, and the present application provides a new antibacterial polyurethane shoe pad material, which has the advantages of extremely water-washing-resistant antibacterial property and does not affect the low density and high resilience of the foam base.

[0008] The second technical problem solved by the present application is to provide a preparation method of the antibacterial polyurethane shoe pad material corresponding to the first technical problem

[0009] To solve the above-mentioned first technical problem, the technical solution adopted by the present application is as follows: an antibacterial polyurethane shoe pad material is composed of components A and B in a weight ratio of 100:68-82, wherein component A includes 50-60 parts of polyether polyol A1, 40-50 parts of polymer polyol A2, 0.3-0.6 parts of a catalyst, 1-3 parts of a chain extender, 1-3 parts of a crosslinking agent, 2-3 parts of water, 2-5 parts of a pore-forming agent, and 1-3 parts of an antibacterial agent; component B is a prepolymer capped with polymethylene polyphenyl isocyanate and dimethyl diphenyl methane diisocyanate based on polyether polyol A1, and the NCO content is 18-23%;

[0010] The polyether polyol A1 has a functionality of 2.5-3.5, a molecular weight of 7000-8000, a molecular weight distribution dispersion coefficient of 1-1.05, an unsaturation degree of ≤0.04 mmol / g, and a relative content of primary hydroxyl groups of 80-90%; the polymer polyol A2 is a graft copolymer of styrene and vinyl acetate based on polyether polyol A1, has a solid content of 30-40%, a hydroxyl value of 15-30 mgKOH / g, and a functionality of 2-4; and the antibacterial agent is a metal complex quaternary ammonium salt antibacterial agent of a metal ion and a quaternary ammonium salt compound.

[0011] The quaternary ammonium salt compound has a structure as shown in general formula (I):

[0012] [(HO-R1-O-)2N + (R2)-R3-Cl]Cl-(I)

[0013] R1 is C2-C4 alkylene, R2 is C1-C4 alkyl, and R3 is C3-C6 alkylene containing a hydroxyl group.

[0014] The metal ion coordinates with the hydroxyl oxygen atom in the molecule of the compound of general formula (I).

[0015] Preferably, the metal ion is selected from one of zinc ion, copper ion or silver ion.

[0016] Preferably, the catalyst is selected from at least one of bis(2-dimethylaminoethyl)ether, triethylenediamine, stannous octoate or butyldistannyl dilaurate; the chain extender is selected from at least one of ethylene glycol (EG), 1,4-butanediol (1,4-BDO), 3-hexanediol or 3-methyl-1,5-pentanediol; the crosslinking agent is selected from at least one of glycerol, diethanolamine or triethanolamine; and the cell opener is a tetrafunctional polyether polyol with sorbitol or glycerol as a starter, a molecular weight of 7000-9000 and an EO end-capped content of 70-80%.

[0017] Preferably, the preparation method of the antibacterial agent comprises the following steps:

[0018] S1. Quaternary ammonium reaction: the tertiary amine compound is reacted with epichlorohydrin at a molar ratio of 1:1 at 60-80°C for 3-5 hours to obtain a quaternary ammonium salt intermediate;

[0019] S2. Metal ion complexation: the quaternary ammonium salt intermediate obtained in step S1 is reacted with a metal salt at a molar ratio of metal ion to quaternary ammonium salt intermediate of 1:2-4 in a solvent at 50-70°C for 2-4 hours, and then the solvent is removed by evaporation to obtain the target antibacterial agent.

[0020] Preferably, the tertiary amine compound is selected from at least one of N-methyl diethanolamine, N-ethyl diethanolamine or N-butyl diethanolamine; the metal salt is selected from at least one of acetate, nitrate or chloride of the metal ion; and the solvent is selected from at least one of isopropyl alcohol and ethanol.

[0021] To solve the above technical problem two, the technical scheme adopted by the present application is as follows: a preparation method of an antibacterial polyurethane shoe pad material, comprising the following steps:

[0022] (1) Preparation of component A: in container A, polyether polyol A1, polymer polyol A2, catalyst, chain extender, crosslinking agent, antibacterial agent, water and cell opener are mixed uniformly according to weight percentage;

[0023] (2) Preparation of component B: in container B, diphenylmethane diisocyanate 30-35 parts is first added and preheated to 40-60°C, then polymethylene polyphenyl isocyanate 30-35 parts is added, polyether polyol A1 30-40 parts is added, and isocyanate prepolymer with isocyanate content of 18-23% is obtained by reacting at 60-80°C for 2-2.5 hours under nitrogen protection.

[0024] (3) mixing the A component with the isocyanate prepolymer of the B component uniformly, pouring into a mold at normal temperature to form and foam, cutting and hot-pressing after curing to obtain the polyurethane foam shoe pad.

[0025] The application provides an antibacterial polyurethane insole material, which is prepared by an antibacterial agent molecule containing two primary hydroxyl groups at the end. The antibacterial agent molecule can form a firm urethane bond with an isocyanate group (-NCO) like a conventional chain extender, thereby becoming a permanent component of the polyurethane polymer molecular chain. This permanently "locks" the quaternary ammonium salt cation and metal ion in the antibacterial functional group in the material, fundamentally solving the problem of easy migration and easy elution of the physical blending antibacterial agent. The antibacterial effect is a high-efficiency "contact type antibacterial". When microorganisms contact the surface of the insole, the negatively charged cell membrane first undergoes strong electrostatic adsorption with the fixed quaternary ammonium salt cation and penetrates the cell wall, and then the metal ion destroys the bacterial cell membrane and enzyme system at the micro interface of the bacteria-material contact to kill the microorganisms. The antibacterial agent does not need to be dissolved to take effect, ensuring the long-term effectiveness of the antibacterial effect. The polyether polyol A1 has a very high molecular weight, and the higher molecular weight makes the polyether molecular chain longer, and the degree of intermolecular entanglement is moderate, which can support a more fluffy cell skeleton during foaming, thereby reducing the overall density. The long molecular chain has better flexibility and molecular chain movement ability. When the insole is under pressure, the molecular chain can absorb energy through deformation, and can quickly return to its original state after the pressure is released, improving the rebound performance. The unsaturation and dispersion coefficient of the polyether polyol A1 are low, which means that the polyether has a narrow molecular weight distribution, few impurities, uniform functionality, and can form a pore size uniform, pore wall structure regular cell system and complete and dense three-dimensional structure during foaming. The polymer polyol A2 provides most of the polyether polyol A1, and the sufficient solid content of the polyether polyol A1 can significantly improve the supportability of the foam. The uniform styrene and vinyl acetate polymers have excellent tensile tear performance, and can also improve the opening of the foam, providing a uniform and delicate cell structure, which is also an important component of the foam that can maintain both rebound and hardness. This uniform cell and complete and dense three-dimensional structure can accurately support the foot pressure, avoid local rebound failure, and reduce the collapse of the cell after long-term use, so that the insole maintains long-lasting high rebound. The dual antibacterial approach combining the organic quaternary ammonium salt and metal ion sterilization mechanism has a wide antibacterial spectrum and an antibacterial rate of more than 99%. After testing, the antibacterial rate of the prepared insole can still reach more than 95% after 100 times of washing, solving the problem of short-term and easy failure of the antibacterial effect of traditional insoles. The antibacterial agent participates in the chain extension reaction without affecting the overall structure and crosslinking density of the polyurethane network, so the foam can completely maintain excellent mechanics such as compression permanent deformation (≤3%) and tensile strength; the antibacterial component is firmly fixed and is not easy to cause potential exposure risk to the human body and the environment, so the safety is high; the process is simple: the antibacterial chain extender can be directly added to the existing polyurethane foaming system without the need for a separate antibacterial agent pretreatment and dispersion step, which simplifies the process flow, is easy to industrialize, and achieves good technical effects. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application. The experimental methods or test methods not mentioned in the following embodiments of the present application are conventional methods in the art, unless otherwise specified.

[0027] Table 1 Raw material list

[0028]

[0029]

[0030] PP-2901 (isocyanate prepolymer) 1 : In a container, 35 parts of diphenylmethane diisocyanate was preheated to 60°C, then 35 parts of polymethylene polyphenyl isocyanate and 30 parts of polyether polyol CHE-2901L were added, and the mixture was reacted at 80°C for 2.5 hours under nitrogen protection to obtain an isocyanate prepolymer with an isocyanate content of 20.3%.

[0031] Zn-QAS antibacterial agent: In a four-necked flask equipped with a condenser and a thermometer, 119 g (1.0 mol) of N-methyldiethanolamine (MDEA) was added. Under stirring and ice water bath cooling, 92.5 g (1.0 mol) of epichlorohydrin (ECH) was slowly added dropwise to control the temperature below 70°C. After the dropwise addition was completed, the temperature was raised to 75°C and the reaction was continued for 4 hours to obtain a (3-chloro-2-hydroxypropyl)-N-methyldiethanolammonium chloride intermediate. To the intermediate, 400 mL of isopropyl alcohol was added, followed by the addition of 109.5 g (0.5 mol) of zinc acetate dihydrate, and the temperature was raised to 65°C for reaction for 3 hours. After the reaction was completed, the solvent isopropyl alcohol was removed by a rotary evaporator to obtain a light yellow waxy solid product, which was the target antibacterial agent.

[0032] In the embodiments of the present application, the quaternary ammonium salt (Zn-QAS) complexed with zinc ions (Zn 2+ ) is described in detail, but those skilled in the art can understand that a series of antibacterial chain extenders with similar structures and functions can be prepared by replacing different tertiary amine initiators (such as N-ethyldiethanolamine) or different metal salts (such as silver nitrate, copper sulfate), which all fall within the protection scope of the present application.

[0033]

Example 1

[0034] By weight, 50 parts of CHE-2901L, 50 parts of CHP-H735, 0.1 part of BDMAEE, 0.5 parts of A33, 1 part of EG, 2 parts of glycerol, 2 parts of Zn-QAS, 2.5 parts of water, and 3 parts of CHK-350D were mixed at 4000 RPM for 1.5 min to obtain component A.

[0035] Components A and B are mixed at a ratio of 100:77 at 4000 RPM for 10 seconds, poured into a room temperature mold for foaming and molding, and then sliced ​​and hot-pressed after curing to obtain antibacterial polyurethane insole material.

[0036] [Examples 2-3 and Comparative Examples 1-4]

[0037] Examples 2-3 and Comparative Examples 1-4 were carried out according to the steps in Example 1, with the difference being the reaction raw materials, the ratio of raw materials, and so on, as detailed in Table 2.

[0038] Comparative Example 5

[0039] By weight, 50 parts of CHE-2901L, 50 parts of CHP-H735, 0.1 parts of BDMAEE, 0.5 parts of A33, 1 part of EG, 2 parts of glycerin, 2 parts of Zn-QAS, 2.5 parts of water, and 3 parts of CHK-350D were mixed at 4000 RPM for 1.5 min to obtain component A. Component A and component B were then mixed at 4000 RPM for 10 s in a 100:78 ratio. The mixture was poured into a room temperature mold for foaming and molding. After curing, it was sliced ​​and hot-pressed to obtain polyurethane insole material. An antibacterial agent was prepared according to patent CN115678097A, and the polyurethane insole material was impregnated in the antibacterial impregnation solution according to the steps in CN115678097A for 2 h.

[0040] Table 2 shows the weight parts of each component raw material in Examples 1-3 and Comparative Examples 1-5.

[0041]

[0042] The performance of the samples obtained in each embodiment and comparative example was tested, including density, Shore C hardness, resilience, tensile strength, elongation at break, tear strength, and compression set. The specific test methods are as follows.

[0043] Density: Tested according to GB / T 6343-2009 after standing at room temperature for 2 days.

[0044] Shore C hardness: After being left at room temperature for 2 days, the test was conducted according to GB / T 10807-2009.

[0045] Rebound resilience: 2 days at room temperature, according to GB / T 6670-2008

[0046] Tensile strength: 2 days at room temperature, according to GB / T 6344-2008

[0047] Elongation at break: 2 days at room temperature, according to GB / T 6344-2008

[0048] Tear strength: 2 days at room temperature, according to GB / T 10808-2006

[0049] Compression set (50%): 2 days at room temperature, according to GB / T 6669-2008

[0050] Antibacterial rate test: 2 days at room temperature, according to JISZ801 test standard:

[0051] 1. Sample preparation: The polyurethane shoe pad material after foaming molding was cut into a sample with a size of 50mm x 50mm x 5mm, and the surface was sterilized by ultraviolet irradiation for 30 minutes.

[0052] 2. Inoculation and culture: 0.1 mL of bacterial solution (concentration of 1.0 x 10 5 CFU / mL) was evenly coated on the surface of the sample, covered with sterile polyethylene film to prevent evaporation, and cultured at a temperature of 34-36℃ and a relative humidity of >90% for 24h.

[0053] 3. Elution and counting: After the culture was completed, the sample was placed in 10 mL of neutralizing solution (containing 0.5% polysorbate-80 physiological saline) and shaken well to elute, and the eluate was gradient diluted and coated on agar plates, and the number of colonies was counted after 48h of culture at 37℃.

[0054] 4. Antibacterial rate calculation: Antibacterial rate = (A-B) / A x 100%, where A is the average number of colonies (CFU / mL) of the blank control group (polyurethane foam without antibacterial treatment), B is the average number of colonies (CFU / mL) of the antibacterial sample group, and the test is performed on Staphylococcus aureus, Escherichia coli, Candida albicans, and Trichophyton mentagrophytes.

[0055] Antibacterial rate after 100 times of water washing: According to JISZ801 test standard, each water washing cycle is 40℃, 30 minutes, and the above antibacterial test is repeated after drying, and the test is performed on Staphylococcus aureus, Escherichia coli, Candida albicans, and Trichophyton mentagrophytes.

[0056] The test results of each sample are shown in Table 3.

[0057] Table 3 Performance test data of polyurethane insole prepared in examples 1-6 and comparative examples 1-5

[0058]

[0059]

[0060] The products of examples 1-6 have the best comprehensive performance: low density, high resilience, low permanent deformation, and long-lasting antibacterial properties, solving the pain points of traditional products.

[0061] As can be seen from example 1 and comparative examples 1-2, the selection of polyether polyol is the key to affecting the density, resilience, and compression permanent deformation of the insole: the long molecular chain of polyether polyol A1 supports the cell skeleton by moderate winding, and has strong recovery ability after deformation; the short chain structure of low molecular weight polyether is prone to be unable to recover due to excessive deformation, resulting in high permanent deformation rate. The high molecular weight and low hydroxyl value of polyether polyol A1 can significantly reduce the density, improve the resilience, and reduce the permanent deformation, which is better than the low molecular weight and high hydroxyl value of polyether polyol.

[0062] As can be seen from example 1 and comparative examples 3-5, the antibacterial rate of the example remains 95%-96% after 100 times of washing, while the silver-based JZ-900 of comparative example 3 decreases to 88%, the organic quaternary ammonium salt DC-5700 of comparative example 4 decreases to 62%, and the antibacterial agent Zn-QAS of the application is permanently fixed by participating in the polymerization reaction through the hydroxyl group, and cannot migrate freely. The antibacterial rate is ≥95% after 100 times of washing, and the contact type synergistic sterilization is achieved. The quaternary ammonium salt cation adsorbs and breaks the membrane, and Zn 2+ penetrates into the cell to destroy metabolism, without the need for dissolution, high-efficiency synergy, without affecting the cell structure, density, and resilience of the foam. The organic quaternary ammonium salt of comparative example 3 and the silver-based antibacterial agent of comparative example 4 can only be effective by migrating from the material to the environment, and the silver-based antibacterial agent is prone to aggregation, acting as a physical crosslinking point or defect point, resulting in a decrease in the mechanical properties of the foam. The organic quaternary ammonium salt affects the microphase separation structure of the polyurethane, and may deteriorate the mechanical properties as a small molecular impurity. Comparative example 5 uses the antibacterial step of patent

[0063] CN115678097A, the antibacterial function is achieved by immersing the material in an antibacterial impregnating solution containing composite zinc oxide and other components after foaming. Although this method can give the material certain antibacterial properties, the antibacterial agent only exists by physical adsorption or surface bonding, and cannot form a chemical bond with the polyurethane molecular chain, resulting in a loss of antibacterial components during washing or use, poor antibacterial durability, and inability to meet the use requirements of insoles which need to be washed multiple times.

Claims

1. An antibacterial polyurethane insole material, comprising components A and B in a weight ratio of 100:68-82, wherein, by weight, component A comprises 50-60 parts of polyether polyol A1, 40-50 parts of polymer polyol A2, 0.3-0.6 parts of catalyst, 1-3 parts of chain extender, 1-3 parts of crosslinking agent, 2-3 parts of water, 2-5 parts of pore-opening agent, and 1-3 parts of antibacterial agent; component B is a prepolymer based on polyether polyol A1, end-capped with polymethylene polyphenyl isocyanate and dimethyl diphenylmethane diisocyanate, with an NCO content of 18-23%; wherein, Polyether polyol A1 has a functionality of 2.5–3.5, a molecular weight of 7000–8000, a molecular weight distribution dispersion coefficient of 1–1.05, an unsaturation degree of ≤0.04 mmol / g, and a relative content of primary hydroxyl groups of 80–90%. Polymer polyol A2 is a polyether based on polyether polyol A1, grafted copolymerized with styrene and acrylonitrile, with a solid content of 30–40%, a hydroxyl value of 15–30 mg KOH / g, and a functionality of 2–4. The antibacterial agent is a metal complex quaternary ammonium salt antibacterial agent composed of metal ions and quaternary ammonium salt compounds. The quaternary ammonium salt compound has a structure as shown in general formula (I): [(HO-R1-O-)2N + (R2)-R3-Cl]Cl - (I) Wherein, R1 is a C2-C4 alkylene group, R2 is a C1-C4 alkyl group, and R3 is a C3-C6 alkylene group containing a hydroxyl group; The metal ions mentioned therein undergo coordination complexation with the hydroxyl oxygen atoms in the molecule of the compound of general formula (I).

2. The antibacterial polyurethane insole material according to claim 1, characterized in that, The metal ion is selected from zinc ions, copper ions, or silver ions.

3. The antibacterial polyurethane insole material according to claim 1, characterized in that, The catalyst is selected from at least one of bis(2-dimethylaminoethyl) ether, triethylenediamine, stannous octoate, or disuccinate dilaurate; the chain extender is selected from at least one of ethylene glycol (EG), 1,4-butanediol (1,4-BDO), 3-hexanediol, or 3-methyl-1,5-pentanediol; the crosslinking agent is selected from at least one of glycerol, diethanolamine, or triethanolamine; and the pore-opening agent is a tetrafunctional polyether polyol with a molecular weight of 7000-9000 and an EO end-capping content of 70-80%, using sorbitol or glycerol as an initiator.

4. The antibacterial polyurethane insole material according to claim 1, characterized in that, The method for preparing the antibacterial agent includes the following steps: S1. Quaternization reaction: Tertiary amine compound and epichlorohydrin are reacted at a molar ratio of 1:1 at 60-80°C for 3-5 hours to obtain quaternary ammonium salt intermediate; S2. Metal ion complexation: The quaternary ammonium salt intermediate obtained in step S1 is reacted with the metal salt in a solvent at a molar ratio of 1:2 to 4 at 50 to 70°C for 2 to 4 hours. The solvent is then removed by evaporation to obtain the target antibacterial agent.

5. The antibacterial polyurethane insole material according to claim 4, characterized in that, The tertiary amine compound is selected from at least one of N-methyldiethanolamine, N-ethyldiethanolamine, or N-butyldiethanolamine; the metal salt is selected from at least one of the acetate, nitrate, or chloride of a metal ion; and the solvent is selected from at least one of isopropanol and ethanol.

6. A method for preparing the antibacterial polyurethane insole material according to claim 1, comprising the following steps: (1) Preparation of component A: In container A, the polyether polyol A1, polymer polyol A2, catalyst, chain extender, crosslinking agent, antibacterial agent, water and pore opener are mixed evenly according to the weight percentage. (2) Preparation of component B: In container B, add 30-35 parts of diphenylmethane diisocyanate according to the weight percentage, preheat to 40-60°C, then add 30-35 parts of polymethylene polyphenyl isocyanate and 30-40 parts of polyether polyol A1, and react at 60-80°C for 2-2.5 hours under nitrogen protection to obtain an isocyanate prepolymer with an isocyanate content of 18-23%; (3) Mix the isocyanate prepolymer of component A and component B evenly, pour it into a room temperature mold for foaming and molding, and after curing, slice and hot press to obtain the polyurethane foam insole.

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